Corrosion resistant iron aluminides exhibiting improved mechanical properties and corrosion resistance

Abstract

The specification discloses a corrosion-resistant intermetallic alloy comprising, in atomic percent, an FeAl iron aluminide containing from about 30 to about 40% aluminum alloyed with from about 0.01 to 0.4% zirconium and from 0.01 to about 0.8% boron. The alloy exhibits considerably improved room temperature ductility for enhanced usefulness in structural applications. The high temperature strength and fabricability is improved by alloying with molybdenum, carbon, chromium and vanadium.

What is claimed is: 
     
       1. A corrosion resistant intermetallic alloy, comprising, in atomic percent, an FeAl iron aluminide containing from about 30% to about 40% aluminum alloyed with from about 0.01 to about 0.4% zirconium, boron in an amount no more than about 0.8% wherein the boron/zirconium ratio is at least about 2 to 1, and from about 0.2% Mo to less than about 0.5% Mo, wherein the alloy exhibits improved room temperature ductility. 
     
     
       2. The alloy of claim 1, wherein the boron/zirconium ratio is between about 2 to 1 and 2.5 to 1. 
     
     
       3. The alloy of claim 1, wherein the Zr is present in an amount of about 0.05%, the B is present in an amount of about 0.24% and the Mo is present in an amount of about 0.2%, wherein the alloy has a tensile ductility of about 11.8% at a temperature of about 70° C. 
     
     
       4. The alloy of claim 1, further comprising from about 0.01% to about 0.07% chromium and from about 0.01% to about 2% vanadium, wherein the alloy also exhibits improved strength at high temperatures. 
     
     
       5. A corrosion resistant intermetallic alloy, comprising, in atomic percent, an FeAl iron aluminide containing from about 36% aluminum alloyed with about 0.05% zirconium, about 0.2% boron and carbon, about 0.2% Mo, about 2% Cr, about 0.2% vanadium, and the balance iron, wherein the alloy exhibits improved room temperature ductility. 
     
     
       6. A corrosion resistant intermetallic alloy, comprising, in atomic percent, an FeAl iron aluminide containing from about 35% to about 36% aluminum alloyed with about 0.1% zirconium, about 0.24% boron and about 0.2% Mo, wherein the alloy exhibits a ductility of about 11.8% at a temperature of about 70° C.